title: Antimicrobial susceptibilities, serogroups, and molecular characterization of avian pathogenic Escherichia coli isolates in Japan.
abstract: In total, 83 avian pathogenic Escherichia coli (APEC) isolates from avian colibacillosis during a period from 2001 to 2006 in Japan were investigated for serogroups, typical virulence factors, antimicrobial susceptibility, and genetic relatedness. The most common serogroup was O78 (30.1%); 80.7% of isolates harbored the iss gene and 55.4% of isolates harbored the tsh gene. Antimicrobial resistance of the isolates was found for ampicillin (77.1%), oxytetracycline (75.9%), kanamycin (36.1%), fradiomycin (33.7%), trimethoprim (25.3%), enrofloxacin (21.7%), and florfenicol (6.0%). Although multiple antimicrobial-resistant phenotypes (three or more antimicrobials) accounted for 54.2% of isolates, no isolate exhibited resistance to all agents tested. The fluoroquinolone-resistant isolates had point mutations in GyrA (Ser83 --> Leu, Asp87 --> Asn) and ParC (Ser80 --> Ile, Glu84 --> Gly). Of 18 enrofloxacin-resistant E. coli isolates, nine isolates belonged to serotype O78. In PFGE analysis, eight of the nine enrofloxacin-resistant O78 isolates were classified into an identical cluster. This suggests that a specific genotype of fluoroquinolone-resistant O78 APEC may be widely distributed in Japan.
authors.affiliation: National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry and Fisheries, 1-15-1, Tokura, Kokubunji, Tokyo 185-8511, Japan. ozawa@nval.go.jp
authors.forename: Manao
authors.initials: M
authors.lastname: Ozawa
authors.forename: Kazuki
authors.initials: K
authors.lastname: Harada
authors.forename: Akemi
authors.initials: A
authors.lastname: Kojima
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Asai
authors.forename: Toshiya
authors.initials: T
authors.lastname: Sameshima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000633:toxicity*; D001483:Base Sequence; D001717:Birds / Q000382:microbiology*; D016000:Cluster Analysis; D027081:DNA Gyrase / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D007564:Japan; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D012703:Serotyping
chemical_list: D000890:Anti-Infective Agents; D027081:DNA Gyrase